Aphidoletes aphidimyza overwinters in the ground as mature larvae or pupae sheltered inside a cocoon. As the weather warms, adults emerge and mate. Females lay eggs either singly or in small clusters among aphid colonies. As larvae are not very mobile, they feed on aphids where the eggs were laid. They suck out the body contents of the aphids. The life cycle from egg laying to adult emergence takes about 18 to 20 days. There are several generations per year.
Cecidomyiid larvae can easily be detected by examining active aphid colonies. The bright pink or orange color makes the predaceous maggots quite visible despite their small size.
In the eastern United States some cecidomyiid species have developed tolerance to organophosphate insecticides and are important predators of aphids in commercial orchards. However, species common in the Pacific Northwest appear to be susceptible to insecticides.
Some species of cecidomyiids are available from biological control insectaries for release in orchards. The efficacy of these species in controlling aphids in Pacific Northwest orchards is unknown.